Health and medical statistics incorporate a variety of data types.
The most common statistics reported are vital (birth, death,
marriage, divorce rates), morbidity (incidence of disease in a
population) and mortality (the number of people who die of a
certain disease compared with the total number of people). Other
common statistical data reported are health care costs, the
demographic distribution of disease based on geographic, ethnic,
and gender variables, and data on the socioeconomic status and
education of health care professionals.

Challenges to finding data

Seekers of health and medical statistics should be aware of the
following challenges in their quest for data.

First, it is important to know that data collection in the United
States is a fairly recent phenomenon. For example, it was not until
1956 that Congress enacted legislation to establish the US National
Health Survey in order to collect statistics on disease, injury,
impairment, disability, and other health related topics. Locating
historical data (pre 1956) will be more time consuming and
consultation with primary resources will be necessary unless an
analysis has already been published on your topic.

Second, data collection is decentralized. Numerous federal, state
and local agencies in additional to not-for-profit organizations
are involved in the collection and dissemination of health related
data. As a result, there may be little to no data in some areas and
duplication of data in others. There may also be variations between
how data is collected and described between these various agencies.
For example, differences in time periods covered, geographic areas,
and sample sizes used to tabulate the data will differ. In
addition, pay special attention to the definitions and coverage
used by each reporting agency as the terminology used may have
different meanings. It is difficult to obtain a precise figure when
it comes to national samples. In most cases the numbers reported
are estimates. Also, reporting standards and definitions change
over time. If your figures seem higher or lower than expected,
check to see if this change reflects actual trends or if the
definition or reporting of your figure has changed. Finally, you
may also see slight variations in the numbers reported between
different agencies. Check to see whether the figures reported are
compiled independently, or if they were taken from other sources.
For example, commercial publishers often repackage government
compiled data. In most cases, the secondary reporting source has
accurately reproduced the original data and conclusions, but when
in doubt, track down the original report.

Third, data collection on a national level takes money and staff to
compile. Only the federal government or a large organization has
the resources to organize and manage large-scale data collection
efforts. Finding data will be easier if you know who is responsible
for collecting data in the area you are studying and the type of
data they collect and publish. Government agencies collect data as
part of a federal mandate; private organizations expend resources
as part of their organizational mission or in response to the needs
of the organization's membership. In either case the collecting
agency has predetermined the need and collection scope for data in
a specific area. It is possible that that data you are looking for
has not been collected, or it has not been analyzed in the manner
in which you need. You may need to obtain the original data and
perform your own analysis. This will be easier if the data was
gathered by a government agency, in which case the data may be
available upon request, in a library, or for purchase. However, if
the data was originally compiled by a private organization, it may
not be possible to obtain the original data sets.

Fourth, data collection and analysis at a national level takes time
to compile. Rarely will you find "real time" data except for
estimates. Most statistics are out of date to some degree by the
time they are published. Just because a report is published in 2000
does not mean the data is from the most recent few years. Current
health data is often based on extrapolations of older data, such as
U.S. Census data, compiled every ten years, or on smaller sample
sizes. Again, check to see when and how the data was collected. In
most cases you will probably see at least a 3-5 year time lag
between data collection and a published report.

Fifth, and compounding the difficulty of locating data at the
national or international level, there is a lack of adequate
subject access through indexing sources (i.e. Medline). Most health
data is compiled and distributed by the federal government. It is
notoriously difficult to track down government resources since
federal reports etc. are as not well indexed. When possible, see if
the reporting agency has the statistics you need. If not, then you
will need to search the journal literature in a bibliographic
database like
MEDLINE or Cancer.gov. It
may be difficult to always determine what type of statistical data
is available from a citation or abstract. When in doubt, read the
article to make sure that you are not missing potential data.

International Data

Locating international health statistics is usually more
problematic than locating U.S. data. Resources, particularly in
developing countries, may not be available to collect data as
extensively or comprehensively as in the United States. Data
collecting efforts therefore vary considerably around the world and
comparative data may not be available. The World Health Organization and the
United Nations are two
international agencies whose mission and budget allow for
international data collecting. Consult the publications of these
agencies first when seeking health and medical statistics. See the
Library's
International Health Research Guide for additional help
locating these elusive statistics.

If you have any questions about resources or services available
to the biomedical sciences community please contact Deb Werner, Biomedical Reference
Librarian or Christa
Modschiedler, Biomedical Bibliographer & Reference
Librarian. You may also email the Crerar Reference Staff.